error met in joint_state_publisher when using rviz to read URDF file

edit

I want to use rviz to visualize my URDF model (it passes check_urdf) and verify if it is correct, as it is generated by Solidworks Add-Ins. While when I roslaunch display.launch, things go wrong. It seems that joint_state_publisher-1 failed. Could someone tell me what is the reason and some possible solutions?

Thank you, I have been stuck here for a long time.

The following is the information in Terminal:

yx@ubuntu://home/yx/Desktop/halobject/src/halobject$ roslaunch halobject display.launch
... logging to /home/yx/.ros/log/8239943a-0f92-11e6-bfff-000c29b98697/roslaunch-ubuntu-7565.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.
started roslaunch server http://ubuntu:39226/

SUMMARY
PARAMETERS
 * /robot_description: <?xml version="1....
 * /rosdistro: indigo
 * /rosversion: 1.11.19
 * /use_gui: True
NODES
  /
    joint_state_publisher (joint_state_publisher/joint_state_publisher)
    robot_state_publisher (robot_state_publisher/state_publisher)
    rviz (rviz/rviz)
ROS_MASTER_URI=http://localhost:11311
core service [/rosout] found
process[joint_state_publisher-1]: started with pid [7583]
process[robot_state_publisher-2]: started with pid [7584]
process[rviz-3]: started with pid [7585]
Traceback (most recent call last):
  File "/opt/ros/indigo/lib/joint_state_publisher/joint_state_publisher", line 343, in <module>
    jsp = JointStatePublisher()
  File "/opt/ros/indigo/lib/joint_state_publisher/joint_state_publisher", line 26, in __init__
    robot = xml.dom.minidom.parseString(description).getElementsByTagName('robot')[0]
  File "/usr/lib/python2.7/xml/dom/minidom.py", line 1928, in parseString
    return expatbuilder.parseString(string)
  File "/usr/lib/python2.7/xml/dom/expatbuilder.py", line 940, in parseString
    return builder.parseString(string)
  File "/usr/lib/python2.7/xml/dom/expatbuilder.py", line 223, in parseString
    parser.Parse(string, True)
xml.parsers.expat.ExpatError: unclosed token: line 1, column 0
[joint_state_publisher-1] process has
died [pid 7583, exit code 1, cmd
/opt/ros/indigo/lib/joint_state_publisher/joint_state_publisher __name:=joint_state_publisher __log:=/home/yx/.ros/log/8239943a-0f92-11e6-bfff-000c29b98697/joint_state_publisher-1.log].
log file:
/home/yx/.ros/log/8239943a-0f92-11e6-bfff-000c29b98697/joint_state_publisher-1*.log

The log file for error is as follows:

[rospy.client][INFO] 2016-05-01 05:53:40,694: init_node, name[/joint_state_publisher], pid[8254]
[xmlrpc][INFO] 2016-05-01 05:53:40,694: XML-RPC server binding to 0.0.0.0:0
[xmlrpc][INFO] 2016-05-01 05:53:40,695: Started XML-RPC server [http://ubuntu:42948/]
[rospy.impl.masterslave][INFO] 2016-05-01 05:53:40,695: _ready: http://ubuntu:42948/
[xmlrpc][INFO] 2016-05-01 05:53:40,695: xml rpc node: starting XML-RPC server
[rospy.registration][INFO] 2016-05-01 05:53:40,695: Registering with master node http://localhost:11311
[rospy.init][INFO] 2016-05-01 05:53:40,697: ROS Slave URI: [http://ubuntu:42948/]
[rospy.init][INFO] 2016-05-01 05:53:40,697: registered with master
[rospy.rosout][INFO] 2016-05-01 05:53:40,697: initializing /rosout core topic
[rospy.rosout][INFO] 2016-05-01 05:53:40,699: connected to core topic /rosout
[rospy.simtime][INFO] 2016-05-01 05:53:40,701: /use_sim_time is not set, will not subscribe to simulated time [/clock] topic
[rospy.core][INFO] 2016-05-01 05:53:40,723: signal_shutdown [atexit]
[rospy.impl.masterslave][INFO] 2016-05-01 05:53:40,726: atexit

I use a normal launch file, which I think won't be wrong:

<launch>
   <param ...